Recently, in the field of endoscopes, there are capsule endoscopes, which are swallowable endoscopes provided with an imaging function and a radio communication function, and a capsule endoscope system for acquiring in-vivo image data imaged by the capsule endoscope has been under development. In the capsule endoscope system, the capsule endoscope is swallowed from a mouth of the subject for observation (examination) and is naturally discharged from the subject. During that time, the capsule endoscope moves in the interior of the subject such as the interior of internal organs including a stomach and a small intestine according to the peristaltic activity, and at the same time, the capsule endoscope images the interior of the subject at predetermined intervals such as at intervals of 0.5 second.
While the capsule endoscope moves in the interior of the subject, the image data imaged by the capsule endoscope is sequentially transmitted to the exterior by a radio communication. A receiving apparatus receives the image data via a receiving antenna provided outside. The receiving apparatus generates the image data based on a radio signal sequentially received via the receiving antenna. Through this process, the in-vivo image data imaged by the capsule endoscope is acquired. The receiving apparatus sequentially stores the acquired image data into its memory. The subject carries the receiving apparatus having the radio communication function and the memory function so as to freely move while the subject swallows the capsule endoscope and naturally discharges it. Thereafter, a doctor or a nurse takes out the image data stored in the memory of the receiving apparatus and feeds it to a display device. The display device then displays on its display the in-vivo image such as an image of internal organs based on the obtained image data. A doctor or a nurse can perform a diagnosis of the subject using the image of internal organs or the like displayed on the display (see, for example, Patent Document 1).
In such capsule endoscope system, the capsule endoscope transmits various kinds of data such as image data to the receiving apparatus by transmitting a radio signal to the receiving apparatus. It is probable that a communication error occurs due to noise or the like while the radio signal is being communicated. A generally used method for detecting and correcting such communication error includes a method in which the capsule endoscope, which is a data transmission side, calculates an error correction code regarding the data to be transmitted, adds the error correction code to the data supposed to be transmitted, and transmits it. The receiving apparatus receives the data transmitted from the capsule endoscope, and at the same time, detects and corrects the error of the received data, based on the error correction code added to the received data.
Patent Document 1: Japanese Patent Application Laid-open No. 2001-231186